1. Field of the Invention
The present invention relates generally to the field of firearms and more specifically to the field of direct gas based firearms.
2. Description of Related Art
Semi-automatic and automatic firearms using a direct gas receiver are known, having been used extensively for recreational and military purposes. While such firearms have numerous objectives, two important objectives include reliability and accuracy.
Conventional direct gas automatic or semiautomatic firearms include a receiver configured to accept a longitudinally reciprocatable bolt assembly, the bolt assembly moveable between a recoiled or retracted position and a battery position. The bolt assembly includes a firing pin that is slidably mounted to the bolt assembly. As is known, the movement of the bolt assembly from the recoiled to the battery position causes a hammer to rotate to a cocked position. A user, by actuating a firearm's trigger, releases a hammer from a cocked position, thereby causing the hammer to strike a firing pin. The force exerted on the firing pin causes the firing pin to move forward until the firing pin strikes a chambered cartridge, thereby firing the cartridge in the firearm.
The firing of the cartridge causes a sudden explosion of gas that propels a bullet down a barrel of the firearm. The gas from the explosion is also used to force the bolt assembly into the recoiled position. A spring operates to resist the movement of the bolt assembly toward the recoiled position and operates to return the bolt assembly back to the battery position. As the bolt assembly returns back to the battery position, the bolt assembly strips a cartridge from the magazine and chambers the next cartridge in the barrel. Unless the weapon is in automatic fire mode, the firearm does not fire another cartridge until the trigger is actuated again.
More specifically, the gas used to force the bolt assembly into the recoiled position is provided through a gas port formed in the barrel. The gas port allows the expanding gas caused by the firing of the cartridge to enter an operatively connected tube that directs the expanding gas back to a key in the bolt carrier group. The expanding gas passes through the key, which is typically a cylindrical hollow rod and enters a chamber in the carrier group. The chamber surrounds a portion of the bolt that is slidably mounted to the bolt group. The increase in gas pressure in the chamber causes the bolt to move away from the battery position toward a recoiled position. In order to provide consistent recoil of the bolt and bolt carrier group, it is necessary that a seal is formed between the bolt and the chamber in the bolt carrier group.
In order to achieve this seal, typically three gas rings are placed in a circular groove formed in the bolt. The gas rings are used to provide a seal between the bolt and the chamber. To aid in the installation, removal, and cleaning of the gas rings, the rings have a gap cut in them that allows the rings to be snapped around the bolt and into the groove formed in the bolt.
Problems exist, however, with respect to the known gas rings. For example, the current gap formed in the gas rings is a radially extending gap. This gap is formed by the opposing ends of the gas ring which define radially extending mating surfaces. The radially extending gaps of adjacent gas rings when aligned, even when compressed, tend to allow the gas to blow by or escape through the gas rings, thereby greatly diminishing the effect of the seal. In the past, to address this problem the gas rings have been installed in a staggered manner such that the gaps in the adjacent gas rings are not aligned along the length of the bolt. With this configuration, there is no direct passage for the expanding gas to blow by the gas rings. While this configuration has been mostly effective, this installation has resulted in a more complex assembly of the firearm. This configuration also requires the user to take care that the ring gaps are not aligned. In addition, this configuration does not eliminate the possibility of the gaps becoming aligned, causing the firearm to not operate properly. As can be appreciated, having the firearm fail due to gas blow-by at an inopportune time may create a hazardous situation to an individual's well being.
Other attempts to solve the problem of gas blow-by have been with the use of a continuous wire ring similar to a key-chain ring. The continuous wire ring has been somewhat effective at preventing blow-by but sometimes causes operation problems when the ring becomes heated causing the entire length of the ring to expand resulting in an inoperable condition, due to binding of the bolt and carrier. Other attempts to solve the problem of gas blow-by have been tried but have been mostly unsuccessful. Consequently, there still exists a need in the art to provide a seal between the bolt and the chamber that prevents the undesirable gas blow-by.